Pneumatic spring.

[2010FRC2272]

If a pneumatic cylinder is pressurized to no more than 60 psi, but mechanically constrained and mechanically released, is this legal? This would be equivalent to an open mechanical spring/trigger mechanism, but would be considerably safer since there would be less access and the pressure could be released automatically at the end of a match.

[GDC]

There is no rule that would prohibit this, as long as the mechanical system does not compress the cylinder when it is part of a closed system and cause the internal pressure to exceed 60psi.